Chemistry Equilibrium PMDC 2020
PMDC Verified Question 73 of 102
For a gaseous phase reaction, when number of moles of reactants and products are equal:
A
The values of \( K_p \) and \( K_c \) are different
B
The value of \( K_p \) is greater than \( K_c \)
C
The value of \( K_c \) is greater than \( K_p \)
D
The value of \( K_p \) and \( K_c \) are the same
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: The value of \( K_p \) and \( K_c \) are the same
Concept:

When the stoichiometry of gaseous reactants perfectly matches the products, the change in moles (\( \Delta n \)) is zero.

Formula:

$$ K_p = K_c(RT)^{\Delta n} $$

Solution:

  • Since moles are equal, \( \Delta n = 0 \).


  • Substitute this into the equation: \( K_p = K_c(RT)^0 \).


  • Any non-zero number to the power of zero equals 1.


  • Therefore, \( K_p = K_c \times 1 \), meaning they are identical.


Why other options are incorrect:

Any discrepancy between \( K_p \) and \( K_c \) fundamentally requires a non-zero \( \Delta n \).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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